Petr Yan has never been the biggest bantamweight, the loudest, or even the flashiest. Yet as he enters UFC 323 to challenge Merab Dvalishvili again, he remains one of the most feared technicians in the division. His record says plenty as a former undisputed champion with 19 career wins, and a highlight reel full of brutality, but his nickname carries even more weight. “No Mercy” isn’t just branding. It’s a preview of what awaits anyone who tries to slow him down.

And if you’ve watched Yan fight, you already know it fits. He doesn’t shout, doesn’t strut, and rarely smiles on fight week. But once the cage door closes, everything changes. So how did the quiet kid from Dudinka end up with one of the most intimidating monikers in modern MMA? And how did that name evolve as he matured from a street-tough brawler into one of the sport’s most disciplined specialists?

How Petr Yan got the ‘No Mercy’ nickname

The exact reason why Petr Yan is called ‘No Mercy’ is still a mystery, but it’s definitely linked to his habit of finishing his fights. In a conversation with the UFC, Yan once said, “Well, it’s just my style of fighting. I’m not forcing the finish, but if I see the opportunity to finish the fight, I will take it. And if my future opponents are getting intimidated while looking at my fights, then so be it, I have my own path, and if there’s anyone standing [in] my way – it may end badly for them.”

And that edge followed him through Russia’s regional scene and into the UFC, where he finished names like Urijah Faber, Douglas Silva de Andrade, and José Aldo en route to the bantamweight throne. Fans didn’t need an explanation. His fights told the story. But if the nickname was born from his natural aggression, what kept it alive was something far more evolved: his transformation into a calculated, disciplined machine.

Petr Yan’s fighting style transformation from aggression to discipline

There was also a time when Yan would show no mercy on the streets. However, with time, he matured as he began spending his time and energy in training. ‘No Mercy’ said, “In the past, I was very aggressive and fierce on the streets. I was spending my energy there. Now I’m a professional, it’s my job, I’ve matured a lot, and I understand that I need to put my energy [into] my professional fights. So outside of fighting, I’m calm, but inside the cage, I’m facing guys who are there to beat me, so I need to be aggressive to break them physically and sometimes even mentally.”

Yan is certainly a man who loves to finish his fights, as seen in his seven wins via KO/TKO, and one via submission. The trend of finishing fights began from his amateur mixed martial arts career. Competing in the Cup of Russia 2014, the bantamweight fighter won two back-to-back bouts via KO. The trend continued when ‘No Mercy’ shifted to the professional realm and fought under the banner of Baikal Storm. Needless to say, he won via a knockout.

When Yan entered Absolute Championship Berkut in 2015, his second bout became his only submission victory via guillotine choke. The lone submission win of his career came in just 47 seconds at ACB 19. His next win came via KO in the first round, when he competed at CSFR. After ending four fights by decision, he put his ACB career to an end with a spectacular knockout at ACB 71.

But what shocked the fighting community was the skills Yan showed when he knocked Teruto Ishihara out with punches in the first round of his debut in the UFC. The fight against Douglas Silva de Andrade ended with a corner stoppage win for Yan. However, when he faced Urijah Faber back in UFC 245, he showed absolutely no mercy when he head-kicked Faber and knocked him out. But his true strength was showcased in the fight against Jose Aldo at UFC 251. It was the bout that got him the bantamweight belt as he defeated Aldo by fifth-round ground and pound.

That’s why his nickname still fits, not because Petr Yan is reckless, but because he’s relentless. What started as youthful aggression grew into a refined philosophy: seize the moment, finish the fight, and never let hesitation take the wheel. As he steps into another title fight at UFC 323, one question lingers: Will “No Mercy” reclaim the belt that made his name echo across the division?